CAJ | 학술논문

位于粤北诸广山岩体东南部的302铀矿床是我国规模较大、埋藏较深的花岗岩型铀矿床之一.该矿床产于印支期油洞岩体和燕山早期长江岩体的断裂蚀变带内,矿区内NWW向基性岩脉十分发育,矿体呈似脉状、扁豆状或透镜状.同位素研究表明,矿石的沥青铀矿Sm-Nd和U-Pb等时线年龄(70 Ma)与油洞岩体(232 Ma)、长江岩体(160 Ma)的年龄相差巨大;主成矿期成矿流体的δD_(H_2O)值为-65‰～-82‰(平均为-75‰),δ~(18)O_(H_2O)值为6.8‰～0.6‰(平均为3.9‰),反映出成矿流体主要由地幔流体组成;方解石的δ~(13)C 值为-8.4‰～-5.3‰, 表明矿化剂ΣCO_2也来自地幔;矿区内辉绿岩的(~(87)Sr/~(86)Sr)i值为0.70861 ～ 0.70882, 花岗岩的(~(87)Sr/~(86)Sr)i值为0.73519 ～ 0.77152,萤石的(~(87)Sr/~(86)Sr)i值为0.71474 ～ 0.71697, 表明成矿组分Sr可能来源于基性脉岩(幔源)与赋矿花岗岩体(壳源),并呈不同程度的混合,而主成矿组分铀主要来源于赋矿花岗岩体.
위우월북제엄산암체동남부적302유광상시아국규모교대、매장교심적화강암형유광상지일.해광상산우인지기유동암체화연산조기장강암체적단렬식변대내,광구내NWW향기성암맥십분발육,광체정사맥상、편두상혹투경상.동위소연구표명,광석적력청유광Sm-Nd화U-Pb등시선년령(70 Ma)여유동암체(232 Ma)、장강암체(160 Ma)적년령상차거대;주성광기성광류체적δD_(H_2O)치위-65‰～-82‰(평균위-75‰),δ~(18)O_(H_2O)치위6.8‰～0.6‰(평균위3.9‰),반영출성광류체주요유지만류체조성;방해석적δ~(13)C 치위-8.4‰～-5.3‰, 표명광화제ΣCO_2야래자지만;광구내휘록암적(~(87)Sr/~(86)Sr)i치위0.70861 ～ 0.70882, 화강암적(~(87)Sr/~(86)Sr)i치위0.73519 ～ 0.77152,형석적(~(87)Sr/~(86)Sr)i치위0.71474 ～ 0.71697, 표명성광조분Sr가능래원우기성맥암(만원)여부광화강암체(각원),병정불동정도적혼합,이주성광조분유주요래원우부광화강암체.
Located at the southeastern part of the Zhuguangshan granite composite in northern Guangdong province, uranium deposit 302 is one of the largest and most deeply buried granite-type uranium deposits in China. In the deposit area there are many NNW striking mafic dikes which intrude into the granite. The ore bodies appear in shape of vein-like, flat beanpod-like and lens-like within the hydrothermally altered fault zones in the Indosinian Youdong granite and early Yanshanian Changjiang granite. The formation age of the pitchblendes in ores (70 Ma) dated with Sm-Nd and U-Pb isochron methods is evidently different from that of the host Youdong granite (232 Ma) and Changjiang granite (160 Ma) dated with zircon U-Pb methods. Study of oxygen and hydrogen isotopes at main metallogenic epoch reveals that the δD_(H_2O) value of ore-forming fluid ranges from -65‰ to -82‰ with the average value of -75‰ and δ~(18)O_(H_2O) ranges from 6.8‰ to 0.6‰ with the average of 3.9‰ which indicate that the ore-forming fluids were mainly composed of mantle-derived fluids. Calcites in the ore veins have δ~(13)C values between -8.4‰ and -5.4‰ which indicate that the ΣCO_2 were also originated from the mantle, while the diabase dikes and granites in the deposit area have initial (~(87)Sr/~(86)Sr)i ratios of 0.70861-0.70882 and 0.73519-0.77152 respectively and the fluorites have initial (~(87)Sr/~(86)Sr)i ratios of 0.71474-0.71697 which implicate that the Sr in the ore-forming fluids may have been a mixture of Sr from mafic dikes and granites. The uranium of the deposit may have been from the granites.